1. Field of the Invention
The present invention relates to a method and an apparatus for regenerating an image holding member in which an image forming substance is stably attached onto a surface of the image holding member by an image forming apparatus such as a copying machine, a facsimile telegraph, a printer, etc., and this image forming substance is removed from the surface of the image holding member.
2. Description of the Related Art
A large amount of printer paper sheets and copying paper sheets has recently been used by office automation (OA). Therefore, a problem about a change for the worse of earth environment is caused by deforestation. This problem is generally solved by only one method. In this method, toner, ink, etc. are removed from a sheet of paper once used, and the paper sheet is crushed in water. This water is removed from the paper sheet by filtration so that the paper sheet is regenerated as a so-called sheet of used paper. However, a new sheet of paper reusable for making a copy or printing has been recently developed. This new paper sheet is reused by removing character images from a paper sheet once used by cleaning.
For example, Japanese Patent Application Laying Open (KOKAI) No. 4-67043 shows such a paper sheet. In this publication, mold-releasing processing is performed with respect to a surface of a sheetlike supporting member, especially, only one face of this sheetlike supporting member. This supporting member as a sheet of copying paper is then marked to discriminate the supporting member from plain paper.
However, such copying paper has the following disadvantages.
(1) This sheet of copying paper is a special sheet of paper having a surface obtained by mold-releasing processing and is not each of sheets of general copying paper and printing paper used so much at present. Therefore, it is difficult to use this surface-processed copying paper as each of the general copying and printing papers.
(2) Accordingly, it is difficult to make a copy by mixing the sheet of surface-processed paper with a sheet of general copying paper.
(3) It is important to make a double-sided copy in view of reuse of resources. Namely, it is important to make a copy on each of front and rear faces of one sheet of copying paper in view of reuse of resources. It is considered that the double-sided copy will become a main current in the future. In such a situation, it is difficult to utilize a sheet of regenerative paper coated with a mold-releasing agent on one face thereof.
(4) An image is formed on the mold-releasing agent so that no image is reliably fixed onto the paper sheet. Accordingly, it is difficult to use such a paper sheet.
Japanese Patent Application Laying Open (KOKAI) Nos. 1-101576 and 1-101577 will next be described.
In each of these publications, an image supporting member forming an image thereon is dipped into an organic solvent for dissolving toner resin for forming the image on this image supporting member. The image is removed from the image supporting member by ultrasonic processing.
However, in this method, problems about environmental pollution, firing, toxicity, etc. are caused by using the organic solvent. Accordingly, it is difficult to use this image supporting member in general offices, homes, etc.
Japanese Patent Application Laying Open (KOKAI) No. 1-297294 will next be described.
This publication shows a method for cleaning an image forming-supporting member. In this cleaning method, the image forming-supporting member is formed by plastic, a metal, a sheet of paper or ceramic having low permeability with respect to a liquid, etc. An image is formed on the image forming-supporting member. This image is heated through a separating material thermally melted so that the image is removed from the image forming-supporting member. However, in this cleaning method, it is necessary to use a sheet of special erasable paper having a surface on which mold-releasing processing is performed. Accordingly, such an image forming-supporting member cannot be used as sheets of general copying and printing papers used so much at present.
For example, the basic system of an electrostatic electrophotographic copying machine is classified into three systems composed of an electrofax system, a zerography system and an NP system. In the electrofax system, a sheet of photosensitive or sensitized paper is required to make a copy. Therefore, the zerographic system is especially a main current at present as a system able to use a sheet of plain paper. In a plain paper copier (PPC) using a sheet of plain paper, there is no restriction about a sheet of copying paper and running cost using the plain paper sheet is low. Further, it is easy to increase a copying speed.
As mentioned above, a large amount of printer paper sheets and copying paper sheets has recently been used by office automation (OA). Therefore, a problem about a change for the worse of earth environment is caused by deforestation. This problem is generally solved by only one method. In this method, ink, etc. are removed from a sheet of paper once used, and the paper sheet is crushed in water. This water is removed from the paper sheet by filtration so that the paper sheet is regenerated as a so-called sheet of used paper. However, a method for reusing a sheet of used paper to make a copy or print has been recently developed. In this method, the used paper sheet is reused by removing character images therefrom by cleaning.
For example, in Japanese Patent Application Laying Open (KOKAI) Nos. 1-101576 (publication 1) and 1-101577 (publication 2), a solvent is used in a method for regenerating an image holding member such as a sheet of paper. In this regenerating method, the sheet of paper attaching toner thereonto is dipped into a soluble solvent of toner resin and a supersonic wave is vibrated in this solvent. Thus, the toner dissolved into the solvent is separated from a surface of the paper sheet.
Further, each of Japanese Patent Application Laying Open (KOKAI) No. 4-300595 (publication 3) and Japanese Utility Model Application Laying Open (KOKAI) No. 4-118500 (publication 4) shows another method for regenerating an image holding member such as a sheet of paper. In this regenerating method, a solvent is attached to a printed portion of a sheet of used paper by a dipping, spraying or coating method, etc. so as to dissolve toner in the printed portion. The dissolved toner is removed from the printed portion by a method using cleaning, air suction, adsorbent contact, mechanical separation or electrostatic adsorption, etc.
For example, Japanese Patent Application Laying Open (KOKAI) No. 1-297294 (publication 5) shows a cleaning method for separating an image from an image holding member without using any solvent. In this cleaning method, the image holding member is formed by plastic, a metal, a sheet of paper or ceramic having low permeability with respect to a liquid, etc. An image is formed on the image holding member. This image is heated through a separating member thermally melted so that the image is removed from the image holding member.
Japanese Patent Application Laying Open (KOKAI) No. 2-255195 (publication 6) shows another method for regenerating an image holding member. In this regenerating method, thermally melted ink or toner is attached by an electrophotographic or thermal transfer system onto a printing member in which a supporting member is coated with a mold-releasing agent. An ink separating member is then overlapped with this printing member and is transmitted between a heating roller and a pressure roller. The ink separating member is separated from the printing member after the ink separating member is cooled. Thus, the thermally melted ink or toner is attached to the ink separating member and is removed from the printing member so that the image holding member is regenerated.
In Japanese Patent Application Laying Open (KOKAI) No. 4-64472 (publication 7), an eraser has at least an endless sheet, a heating roller, a cooling roller, a pressing roller and a driving portion. The endless sheet has thermally melted resin on a surface thereof. The heating and cooling rollers are arranged to support and rotate the endless sheet. The pressing roller presses a sheet of erasable paper having a mold-releasing processed surface against resin thermally softened or melted. The driving portion is used to move the endless sheet, the heating roller, the cooling roller and the pressing roller in association with each other. In one example of the mold-releasing processing on the paper sheet surface, a surface of a sheet of unused copying paper is coated with a mold-releasing agent such as a silicon sealant and is then dried.
Japanese Patent Application Laying Open (KOKAI) No. 4-82983 (publication 8) shows an apparatus for removing an image forming substance from a sheet of paper. This removing apparatus has two parallel rollers, a heater, a scraper and a separator. The two parallel rollers come in press contact with each other and are rotated to make the paper sheet pass through a press contact portion. The heater heats at least one of the two rollers. The scraper separates the paper sheet passing through the press contact portion from the rollers. The separator removes an image forming substance attached onto the rollers therefrom.
In the regenerating method and the regenerating apparatus shown in each of the above publications 1 to 4 using a solvent, an organic solvent for dissolving image forming toner resin on the image holding member is used to remove an image from this image holding member. However, it is not suitable to generally arrange and use such an organic solvent in offices, homes, etc. in consideration of influences of the organic solvent on human body and environment. It is necessary to properly and separately use plural types of solvents in accordance with kinds of binder resins such as toner and paint so that processed objects are limited. Further, when toner is dissolved by a solvent, probability of reattachment of this toner into a fibrous tissue of the paper sheet is increased so that a removing rate of the toner is totally reduced. Further, no problem about dyeing can be easily avoided and cost of a sheet of regenerated paper is economically high in comparison with a general system for regenerating a sheet of used paper.
No solvent is used in the regenerating method and the regenerating apparatus shown in publications 5 to 7. However, in this case, a sheet of erasable paper having a mold-releasing surface must be used. Accordingly, it is difficult to apply these regenerating method and apparatus to general sheets of copying and printing papers, etc. used so much at present. Since an image is formed on a mold-releasing agent, fixing force of the image is naturally reduced. Further, a copy must be made by discriminating erasable and plain paper sheets from each other so that no copying operation is efficiently performed. It is also difficult to make a copy in a real state in which the erasable and plain paper sheets are mixed with each other.
In particular, for example, the following problems are caused when a mold-releasing agent such as a silicon sealant is coated and dried to provide a mold-releasing property on a paper sheet surface as described in the above publication 7. Namely, a paper fibrous structure on the paper sheet surface is maintained as it is when only the mold-releasing agent such as a silicon sealant is coated and dried. An endless sheet having thermally melted resin on a surface thereof is adhered onto an image face of the erasable paper sheet to mechanically separate the image from the erasable paper sheet in a heating state. However, it is difficult to completely remove the image from the paper sheet until toner resin of the image permeating into clearances between paper fibers. Accordingly, regenerating efficiency is insufficient.
It is important to make a double-sided copy in view of reuse of resources. Namely, it is important to make a copy on each of front and rear faces of one sheet of copying paper in view of reuse of resources. It is considered that the double-sided copy will become a main current in the future. Accordingly, regenerating efficiency is reduced in a method for coating one face of the paper sheet with a mold-releasing agent. The silicon sealant permeates a sheet of copying paper even when the mold-releasing agent is coated and dried on both side faces of the paper sheet. As a result, a semi-transparent sheet of copying paper is obtained. Accordingly, no images can be clearly seen in the case of the double-sided copy.
No solvent is also used in the regenerating method and apparatus shown in publication 8. An image forming substance is removed from a recorded image holding member in which an image is recorded onto a sheet of normal paper having paper fibers exposed onto a surface thereof. Accordingly, there is a fear that the paper fibers are separated from the paper sheet surface together with the image forming substance in removal thereof, thereby damaging a chartaceous property. This is because the image forming substance is firmly fixed to paper fibers on a surface of the image holding member. For example, the image forming substance is firmly fixed to the paper fibers by melting and attaching the image forming substance having thermally melted resin as a principal component onto the image holding member in a fixing process of an electrophotographic system.
When the above ink separating member, the endless sheet or each of the rollers is heated and pressurized to efficiently remove the image forming substance from the image holding member, fixing force of the image forming substance on the image holding member is conversely increased in accordance with various kinds of fixing conditions. Accordingly, it is difficult to remove the image forming substance from the image holding member in a certain case.